Re: max ext2 fs size

From: willy@thepuffingroup.com
Date: Thu May 11 2000 - 15:08:13 EST


On Thu, May 11, 2000 at 02:52:41PM -0300, Rik van Riel wrote:
> Yes. I believe it is limited to about 2 TB (yes, TERAbyte).

hmm.. it's limited by the triple-indirect block.

assume 4k blocks (you would be foolish to store huge files on 1k blocks):

each indirect block can store the addresses of 1k blocks, therefore
each dind block stores 1M blocks and the tind block stores 1G blocks.
1G * 4k = 4TB. Adding in the dind, sind and direct blocks, we get:

4TB + 4GB + 4MB + 48kB = 4402345721856 bytes.

> If you have >2TB of disk and run into this limit, it shouldn't
> be more than a minor inconvenience to move to a 64-bit platform.
> I don't want to imagine the fsck times on a 2 TB filesystem though ;)

this is a limitation of ext2 rather than the VFS. you're thinking of
the VFS limit on 32-bit platforms. You actually can go larger on the Alpha
because it has an 8k page size, therefore you can have an 8k block size
which lets you go to 16TB (+ epsilon).

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